Relational data is the key to a database.
It basically means that the data in one table relates to the data in another table.
In an HR database you’ve got two tables, Employee and Department.
<pre>CREATE TABLE Department
CREATE TABLE Employee
These tables are related to each other through the DepartmentId column in each table.
The first table is the MASTER and the second is the DETAIL table, it is important that the Department column to be unique (primary key) in the master table, for to have a clear one to many (or 0) relation between the records from the two tables.